This
is a photo of the very rare, blue version of the ARP 2600. There
are approximately 20 of these beautiful machines known to be in
existence according to our estimates. I love the look of the metal
cabinet 2600's, but Alan Pearlman didn't speak highly of the enclosure
when I first mentioned the old metal cabinet 2600s to him when we
first met. "We had an aircraft fuselage engineer design the
cabinet for the very first 2600's, what a nightmare! It was odd
looking, very difficult to service, and the corners tended to crack.
I took the front panel (the front panel layout was designed by Alan
himself) got rid of everything else, and came up with the tolex
covered shuke type cabinet". This
was explained to me by Alan R. Pearlman as he drove me around town
and to lunch at a local Japanese restaurant in his black Saab.The
shuke is the inside angled tolex section that the front panel is
bolted to in a standard 2600P/2601. Over the years, it's obvious
that Alan's cabinet solution made the machine much more roadworthy
and serviceable. But you just can't help appreciating the "Mod"
appearance of the first 2600's. Alan also talked quite a bit about
Dennis Colin and described him as a genius, He was the electronic
engineer who along with Alan, designed many of the 2500 and 2600s
critical audio processing circuits. Dennis passed away last November
(2015) and he will be missed.

The
2600 uses microchip technology in all of its gain stages! The first
2600's, like the one pictured above, used hi-fi chips (Teledyne)
with a high slew rate. Although these chips sound great, they were
very unreliable and prone to latch up. Around 1972, plagued by failures
in the field, ARP was forced to change these chips to a much more
reliable type (National Semiconductor LM-301 or SL-1998) The problem
is that they slew the wave shape producing a muffled sound. The
LM-301 is classified as a general purpose amplifier, and is considered
inadequate for audio by present standards. Nearly all the standard
production gray-face 2600's use the LM301. This is the main reason
why the legendary Blue Marvins sound better! If your 2600 doesn't
look like the one in the photo above, and odds are it doesn't, your
2600 is not using the original circuitry and does not sound the
way it was originally intended to sound by the ARP engineers.

The C.M.S. Audio path upgrade restores your 2600 to the original
performance specs. If you're going to use your 2600 in a modern
digital/analog studio, we strongly recommend the CMS Audio Path
Upgrade. If you want to keep your 2600 totally original for collector
reasons, CMS offers full restoration and repair services back to
ARP factory spec.

STAGE
ONE UPGRADES / MODIFICATIONS FOR THE ARP 2600

Updated
September 25 2017

These
upgrades are internal audio improvements to the circuitry of the
2600.

Listed
in order of popularity:

POWER
SUPPLY REBUILD - (ALL MODELS) - 189.00

The
power supply in your 2600 is about 30 to 40 years old. Certain
components in the ARP 2600 power supply have a shelf life /
working life of 20 years maximum. If your power supply has not
been serviced in the last 20 years, chances are your power supply
is not up to spec. This can result in excessive noise, ripple,
and instability. Your power supply is removed. All critical
components are professionally replaced. Stability and load are
tested using factory specs. Rebuilt ARP power supplies are available
from CMS but we require the old power supply in exchange.

AUDIO
PATH UPGRADE PACKAGE - (ALL MODELS) - 399.00

This
mod replaces all gain stages in the 2600 console with audiophile
grade components for crystal-clear highs and a deep low end,
while still maintaining the distinctive character of the 2600.
Upgraded sections include: lag processor, voltage processors,
reverb stages, pre amp, VCF mixer, output mixer, output buffers,
etc. We also fix the annoying VCA thump. Noise in the reverb
section is reduced by 35%. Filter headroom is increased by a
factor of 2! Stability and sound improvement guaranteed. Later
model 2600s (almost all wood / tolex 2600s) use inferior sounding
gain stages that severely impede the true sound of your 2600.
Earlier 2600's (Blue Marvins and Gray Meanies) use "high
slew rate" chips that sound much clearer.Restore
your 2600 back to the specs that the original ARP engineers
intended! Don't be fooled by imitations from "noob techs"
or DIY attempts. If the Audio Path Upgrade is not performed
correctly, it can become unstable and lead to high frequency
self oscillation of all the amplifier sections!

17
INCH REVERB TANK - (ALL MODELS) - 99.00

Ever
wonder why later model 2600s have such a lame reverb? Later
model 2600s use smaller reverb tanks with a shorter delay time
than earlier 2600s made by ARP. The only reason I can find for
this change is economic. Our brand new reverb tanks use 3 springs,
counter wound and placed in parallel for a rich, full sound.
This mod restores your reverb sound back to the original "Blue
Marvin / Gray Meanie" configuration.

MOOG
STYLE FILTER MODULE - 4012cx - (ALL MODELS) - 399.00

The
4012 filter was used from 1971 (blue Marvin) to the middle of
1976. If your 2600 is a gray face, It probably utilizes the
4012 module. The 4012 is a ladder type filter using discrete
transistors. The original 4012 made by ARP is prone to instability.
The 4012 replacement filter by CMS is guaranteed stable yet
uses the exact circuit that ARP used. Better quality components
and personal attention to craftsmanship yield a filter of superior
sonic characteristics! See the Sub-module
section for more info.

FILTER
MODULE UPGRADE - (4072) - (LATER MODELS) - 99.00

All
later ARP filters (after 1975) have a cutoff frequency limit
of 11 kHz. This mod upgrades the cutoff frequency range from
11 kHz to 28 kHz. We also upgrade the filter output amp and
control summing amp. This is a necessity for all un-encapsulated
filters. A cost effective alternative to a 4012 module.

VCA
MODULE UPGRADE - (4019) - (LATER MODELS) - 125.00

If your VCA module is un-encapsulated, we can give it crystal
clear highs and a deep low end. Also provides lower distortion
and a faster slew-rate. If you have an encapsulated ARP VCA,
this upgrade is not available, but improved un-encapsulated
replacement modules are available, see sub-modules page, model
4019cx.

The ARP 2600C restored
by CMS.

STAGE
TWO UPGRADES / MODIFICATIONS FOR THE ARP 2600

These
upgrades / modifications are more extensive and time consuming
than the above. They usually involve partial to complete
disassembly, front panel machining, re-assembly etc.

Listed
in order of popularity:

SYNC
SWITCHES - 199.00

Two
independent high quality miniature toggle switches that
syncs VCO-1 to VCO-3, and VCO-2 to VCO-3 This setup enables
dual sync (two separate harmonics) if desired. Stability
guaranteed, unlike the factory version. You must have
at least 1 un-encapsulated VCO to install this mod.

ENVELOPE
GENERATOR RANGE EXPANDER SWITCHES - 179.00 for both

Miniature
high quality toggle switches that provide 2 additional
time ranges for the attack, decay and release time of
the ADSR generator and the attack and decay time of the
AR generator.

ADSR:
The ADSR is quick in a stock 2600. The 3 position switch
we install gives you a x1(factory speed), a x2 and a x3
speed, providing much longer times previously unavailable
on a 2600.

AR:
Conversely, the AR generator in a 2600 is quite sluggish
in certain situations. This mod now includes an upgrade
of the AR circuit. In addition to the normal X1 mode,
the high quality 3 position switch provides a new high
speed mode for sharper attacks, as well as a X2 mode for
longer attack and release times.

The
filter tracking on a 2600 is fixed at 1v per octave. This
is quite limiting especially if you are shooting for natural
textures. This mod provides a high quality miniature rotary
potentiometer that adjusts the filter tracking ratio from
0 to 1v/octave.

POWER
SUPPLY UPGRADE - (ALL MODELS) - 379.00

The
power supply in your 2600 is about 30 to 40 years old.
This upgrade features a professionally installed, high
power, highly stable, military spec power supply. This
power supply features a high speed regulation circuit
that reduces cross-talk between sub-modules in your 2600
system. The overall sound quality and oscillator purity
are noticeably improved. Warning: These power supplies
must be installed by a professional. Incorrect installation
of a power supply upgrade can lead to system instability.

STAGE
THREE UPGRADES / MODIFICATIONS FOR THE ARP 2600

These
major upgrades / modifications are very extensive and
time consuming. These mods are designed for users that
are seeking to professionally "Hot Rod" their
ARP 2600 to the max. They require complete disassembly,
front panel machining, rewiring, and the power supply
upgrade.

Listed
in order of popularity:

VCO OCTAVE SWITCHES - 115.00
each

This variable version octave switch
has a position toggle and a potentiometer to dial in any
desired interval over a 2 octave range. This upgrade uses
the same high quality miniature toggle switches, military
spec potentiometers that were used on the ARP 2500 system
including a high quality 2500 style knob.

We install 2 LFOs below the voltage
processors. They have triangle and square outputs and
also have LED indicators included. This mod, as all our
others for the ARP 2600, features high quality Switchcraft
jacks, military spec potentiometers and ARP 2500 style
knobs. Requires the power supply upgrade.

COMPARATOR / DISTORTION - 199.00

This can be used to square up a waveform.
It also makes a good distortion device according to John
McEntire from Tortoise. Includes LED indicator.

SCHMITT TRIGGER - 189.00

This useful circuit is sometimes
called a trigger detector or gate detector. It is typically
used to trigger the envelopes when controlling the unit
externally by guitar or any external source. This circuit
often frees up the envelope follower so it can modulate
the filter for an auto wah wah effect, synced VCOs etc.
An LED indicator also provided. The input jack is normalized
to the output of the envelope follower.

24Db
DUAL MODE FILTER - MODEL 2621- special order - call

The
one key element missing in a 2600 is a high-pass filter
with resonance and associated coupling circuitry. The
CMS 2620 is a dual mode, 24Db (Low-pass/High-pass), discrete,
transistor ladder filter from the CMS 9000 series modules,
Installed in the left speaker section. This original CMS
design features an innovative circuit that extracts a
high-pass response from a 24BD discrete ladder filter
circuit producing a unique sound and beautiful resonance
quite different from the existing low-pass filter in the
2600. In addition, the volume of the filter output does
not drop off drastically as the resonance is increased
as all other ladder filters do. This also makes the low-pass
output quite useful as an alternative sounding 24db low-pass
filter. Complete with anodized face plate, high quality
controls, 1/8 inch Switchcraft normalized patching. Special
link switch enables the coarse frequency control knob
of the 2627 to control both filters for a truly remarkable
sounding band-pass function (24Db x 24Db). The resonance
on the high-pass function is also very unique and distinctive.
Requires the power supply upgrade. Now comes with voltage
controlled resonance.

VCO
/ 4 CHANNEL MIXER / INVERTER - MODEL 2627 - special order
- call

Installed in the right speaker section, this VCO utilizes
the same exact circuitry used in the other VCO's in your
2600 to assure exact tracking and pitch stability characteristics.
All four waveforms are available as well as pulse width
modulation. Low frequency mode and normalized patching
are also provided. The mixer section serves as a high
quality audio mixer with the inputs either normalized
to all 4 outs of VCO-4 or externally patched. The mixer
can also be used as a voltage summer or inverter. This
major upgrade uses high quality Switchcraft jacks, military
spec potentiometers and ARP 2500 style knobs. Requires
the CMS power supply upgrade.

A fully
modified 2601

Many of our customers prefer to have their machine in
original condition. We offer full restoration services that restore
your 2600 to original ARP factory specifications. Call or email
Phil at CMS to schedule a free estimate on your ARP 2600. Every
2600 restoration varies widely depending on condition, road use,
storage conditions, poor servicing, substandard aftermarket sub-modules
and moisture damage. Estimates are not available by phone or email.